A DUAL VIBRATION-COMPENSATING APPARATUS

Abstract: A dual vibration-compensating apparatus for counteracting unbalanced moments of two different orders generated by a main engine of a vessel. The apparatus comprises a first and a second compensating unit (51, 52). Each unit comprises an eccentric mass rotating with a shaft, said shafts being interconnected through a transmission having an integer transmission ratio and driven at a rpm being a multiple of the rpm of the engine of the vessel by means of a driving motor (84) and a control and synchronising device. The shafts (57; 72, 73) are essentially perpendicular to one another and the first compensating unit (51) comprises at least one rotary body (60) with an eccentric mass and with a rotary body part (60F) being fixedly mounted on the first shaft (57) and a second rotary body part (60L) being releasably mounted on the first shaft (57). The second compensating unit (52) comprises two pivotally arranged shaft parts (72, 73) on each of which a rotary body with the same eccentric mass is mounted comprising a rotary body part (70F, 71F) being fixedly mounted on the shaft and a rotary body part (70L, 71L) being releasably mounted on the shaft parts (72, 73). The shaft parts being interconnected through a transmission (81, 82, 63) so as to rotate in opposite directions.

Description: Title: A Dual Vibration-Compensating Apparatus Technical Field The invention relates to a dual vibration-compensating apparatus for counteracting unbalanced moments of two different orders generated by the main engine and comprising a first and a second compensating unit, each comprising an eccentric mass rotating with a shaft, said shafts being interconnected through a transmission having an integer transmission ratio and driven at a rpm being a multiple of the rpm of the engine of the vessel by means of a driving motor and a control and synchronising device. Background Art It is known to compensate the unbalanced moments of the first, second and/or higher order from marine engines by means of a vibration-compensating apparatus such as the type disclosed in Danish patent application No. 6978/88. It is further¬ more known that such vibration-compensating apparatus also may be used to compensate for other unbalanced forces or moments, for instance from the propellers. Furthermore, EP-Bl-0.010.973 discloses a compensating apparatus intended to compensate for vertical unbalanced moments of the first and second order. Each of the compensating units of said compensating apparatus comprises a single rotary body generating a non-variable rotating force component. Disclosure of the Invention The object of the present invention is to provide a dual vibration-compensating apparatus of the type stated in the introduction, of a very simple structure and making it possible to regulate the resulting force from both compensating units. The dual vibration-compensating apparatus according to the invention is characte¬ rised in that the shafts are essentially perpendicular to one another and that the first compensating unit comprises at least one rotary body with an eccentric mass and with a rotary body part being fixedly mounted on the first shaft and a rotary body part being releasably mounted on the first shaft, and that the second com¬ pensating unit comprises two pivotally arranged shaft parts, a rotary body with the same eccentric mass being mounted on each shaft part, each of said rotary bodies comprising a rotary body part being fixedly mounted on the shaft and a rotary body part being releasably mounted on the shaft parts, said shaft parts being interconnected through a transmission so as to rotate in a opposite direc¬ tions. Consequently, a dual vibration-compensating apparatus is provided which can compensate for unbalanced moments or forces being perpendicular to one another and whereby the size of the resulting force generated by the rotary bodies may be varied for both compensating units. Further, the direction of the force generated by the second compensating unit having two opposite rotating masses can be regulated by changing the mutual position of the two rotating masses. A universal¬ ly applicable vibration-compensating apparatus is thereby obtained by means of which it is possible to compensate for the main engine's unbalanced moments of the first and second order by arranging the compensating in the rear end of the vessel. According to the invention, the first compensating unit may comprise two rotary body parts mounted on coaxially arranged shaft parts and each having a fixed and releasable rotary body part, said shafts parts being connected so as to rotate in opposite directions. This embodiment has the advantage that it is possible to change both the size and the direction of the resulting force generated by both compensating units. Further, according to the invention, the transmission between the two vibration- compensating units may comprise at least one coupling being releasable to enable turning of the shaft of the first compensating units relative to the shaft parts of the second compensating units. As a result, it is possible to change the phase angle between the two compensating units relatively fast by releasing the coupling, turning the shaft of one of the compensating units relative to the other and engaging the coupling in the new relative position of the two shafts. Finally, according to the invention, the transmission between the two shaft parts of the second compensating units may comprise a releasable coupling being releasable to enable turning of the two shaft parts relative to each other. Conse- quently, the direction of the second compensating unit may be changed relatively fast by releasing said coupling, turning the two shaft parts in relation to each other and engaging the coupling in the new relative position of the two shaft parts. Advantageous embodiments of the invention appear from the sub-claims and the detailed description. Brief Description of the Drawings The invention is described in greater detail below with reference to the accom¬ panying drawings, in which Fig. 1 is a diagrammatic, top view of a vibration-compensating apparatus, Fig. 2 is a sectional view along the line A- A in Fig. 1, and Fig. 3 is diagrammatic, vertical sectional view through a vibration-compensating apparatus according to the invention. Best Mode for Carrying out the Invention Figs. 1 and 2 show a vibration-compensating apparatus comprising a housing 1 having a first end wall 2, a second end wall 3 and a partition wall 4. Between the first end wall 2 and the partition wall 4 a first circumferential wall 5 is arranged. In a corresponding manner a second circumferential wall 6 is arranged between the partition wall 4 and the end wall 3. The housing 1 is assembled by staybolts (not shown) extending in between the two end walls 2,3. The second end wall 3 forms the base of the housing and is provided with mounting holes (not shown). A dual shaft comprising an inner central shaft 8 and a hollow shaft 9 arranged pivotally thereon is supported by the end walls 2 and 3 and the partition wall 4 by means of bearings. The central shaft comprises a first shaft portion 10 of a larger diameter and a second shaft portion 11 of a smaller diameter. The hollow shaft 9 is arranged on the small shaft portion 11 of the central shaft 8 and has the same outer diameter as the first shaft portion 10 of the central shaft 8. At its outer end 12, the large shaft portion 10 of the central shaft 8 is pivotally arranged relative to the other end wall 3 by means of a bearing 13. In the trans¬ ition area to the second small shaft portion 11 , the first shaft portion of the central shaft 8 is pivotally arranged in the partition wall 4 by means of a bearing 14. In a manner corresponding thereto, the hollow shaft 9 is at its lower end pivotally arranged relative to the partition wall 4 by means of a bearing 15, and at its upper end pivotally arranged relative to the upper end wall 2 by means of a bearing 16. Finally, the hollow shaft is pivotally arranged by means of a bearing 18 on the small shaft portion 11 of the central shaft. In the large shaft portion 10 of the central shaft 8 a rotary body 19 is arranged and being essentially shaped like the sector of a circle when seen in axial direction and thus having an eccentric centre of gravity. The rotary body 19 comprises a rotary body part 19F being fixedly mounted on the large shaft portion 10 of the shaft 8 and a releasably mounted rotary body part 19L being releasable for tur¬ ning relative to the fixed rotary body part 19F. In a corresponding manner, a rotary body 20 is mounted on the hollow shaft, said body also being shaped like sector of a circle when seen in an axial direction and comprising a rotary body part 20F being fixedly mounted on the shaft and a releasably arranged rotary body part 20L. The releasably arranged rotary body parts 19L, 20L may be released and turned by supplying pressurised fluid to the mounting area between the shaft and the rotary body part, for instance as disclosed in Danish patent application No. 6978/88. The two shafts 8, 9 are interconnected through a transmission so as to rotate in opposite directions. The transmission comprises a first gear wheel 23 fixed to the hollow shaft 9 at the upper end 17 thereof, and an engaging second gear wheel 24 mounted on a shaft 25, which in turn is pivotally arranged coaxially with the dual shaft 8,9. On the outer end of the small shaft portion 11 of the central shaft 8, a pulley 26 is mounted. A corresponding pulley 27 is mounted on the outer end of the second shaft 25. A third pulley 28 is mounted on the output shaft of a driving motor 29, preferably a servomotor, driving the two pulleys 26,27 in the same direction via a belt 30, whereby the central shaft 8 and the hollow shaft 9 and consequently also the rotary bodies 19,20 connected thereto rotate in opposite directions. As the rotary bodies have the same eccentric mass, a resulting force component of zero is generated in one direction and in a direction perpendicular thereto a harmonic force component is generated which varies between zero and twice the force of each rotary body. As the releasable rotary body part 19L.20L of the rotary bodies may be turned relative to the fixed rotary body part 19F, 20F, the force generated by each rotary body may be regulated and the resulting force component may thereby be adjusted continuously from zero to four time the force of each rotary body part, when said parts have an equal eccentric mass. Fig. 3 illustrates an embodiment of the dual vibration-compensating apparatus according to the invention comprising a first compensating unit 51 and a second compensating unit 52 arranged so as to rotate about axes perpendicular to each other and thereby to provide oscillating forces in mutually perpendicular planes, including mutually perpendicular forces . The first compensating unit 51 comprises a housing 53 having two end walls 54,55 and a circumferential wall 56 fixed between the two end walls 54 and 55 by means of staybolts (not-shown). The compensating unit 51 is intended to be mounted in the position shown and is therefore provided with mounting holes (not-shown) in the lower end wall. A shaft 57 is pivotally supported by means of bearings 58,59 in the upper and lower end wall 54 and 55, respectively. A rotary body 60 is mounted on the shaft 57, said body being essentially shaped like the sector of a circle when seen in axial direction and thus having an eccen¬ tric centre of gravity. The rotary body 60 comprises a fixed rotary body part 60F and a releasably mounted rotary body part 60L being releasable for turning relative to the fixed rotary body part 60F. The two rotary body parts 60F and 60L is preferably of equal size, whereby the rotating unbalanced force generated by the rotary body may be varied between zero and twice the unbalanced force of each of the rotary body parts. To enable turning of the releasable rotary body 60, the shaft is provided with a passage 61, through which pressurised fluid may be supplied to the mounting area between the shaft 57 and the releasable rotary body part 60L. The shaft 57 is provided with an upper end projecting out of the housing, onto which a bevel gear 63 is mounted via a coupling 62 releasable for turning, for instance a conical friction coupling. The second compensating unit 52 comprises two rotary bodies 70,71 being shaped essentially like the sector of a circle when seen in axial direction and therefore having an eccentric centre of gravity. Each of the rotary bodies 70, 71 is pivotally supported in a housing 74,75 comprising two end walls 76,77 and a circumferen- tial wall 78 being fixed between the end walls by means of staybolts (not shown). Each rotary body 70,71 comprises a rotary body part 70F, 71F being fixedly mounted on the shaft and a releasable rotary body part 70L, 71L being arranged releasable for turning. The releasable rotary body may be released by supplying pressurised fluid to the mounting area thereof on the shaft through a passage 79,80. The shafts 72,73 are each provided with a drive pinion 81,82 at the free end facing one another, said drive pinion engaging the bevel gear 64 on the shaft 57 of the first compensating unit 51. The drive pinion 82 is arranged on the free end of the shaft by means of a coupling 83 being releasable for turning, for instance a conical friction coupling. The engagement between the bevel gear 64 and the drive pinions 81,82 causes the shafts 72, 73 and thereby the rotary bodies 70,71 to rotate in opposite directions at the same rpm, which in the example shown is twice the rpm of the vertical shaft 57. As it is possible to turn the releasable rotary body parts 70L, 71L relative to the fixed rotary body parts 70F, 7 IF, the resulting oscillating force may be varied continuously from zero to four times the force of each rotary body part, when the eccentric mass for said parts is the same. The releasable coupling 83 makes it possible to regulate the direction of the oscillating resulting force of the second compensating unit relatively fast, while the releasable coupling 62 makes it possible to regulate the phase angle relatively fast between the two compensating units 51,52 relative to one another. A driving motor 84, preferably a servomotor, is arranged on the housing 74 driving the shaft 72 via a planet gear 85 and a transmission. The transmission comprises a pulley 86 mounted on an output shaft of the planet gear and a second pulley 87 mounted on a projecting shaft end of the shaft 72 and a belt 88 between the two pulleys 86,87. The dual vibration-compensating apparatus may be modified in many ways wi¬ thout thereby deviating from the scope of the invention. Instead of the rotary bodies arranged on each side of the shaft 57 of the first compensating unit, the second compensating unit 52 may be formed of a compensating unit provided with rotary bodies arranged on the same side thereof, for instance a compensating unit as the one described above or the unit disclosed in Danish patent application No. 6978/88. As a result, the two compensating units may be interconnected by means of a bevel gearing. Further, the lower compensating unit may be formed of a compensating unit with two opposite rotating rotary bodies, such as the one described above or the compensating unit according to Danish patent application No. 6978/88.

Claims: Claims 1. A dual vibration-compensating apparatus for counteracting unbalanced moments of two different orders generated by a main engine of a vessel and comprising a first and a second compensating unit (51,52), each comprising an eccentric mass rotating with a shaft, said shafts being interconnected through a transmission having an integer transmission ratio and driven at a rpm being a multiple of the rpm of the engine of the vessel by means of a driving motor (84) and a control and synchronising device, c h a r a c t e r i s e d in that the shafts (57;72,73) are essentially perpendicular to one another and that the first compen- sating unit (51) comprises at least one rotary body (60) with an eccentric mass and with a rotary body part (60F) being fixedly mounted on the first shaft (57) and a rotary body part (60L) being releasably mounted on the first shaft (57), and that the second compensating unit (52) comprises two pivotally arranged shaft parts (72,73), a rotary body (70, 71) with the same eccentric mass being mounted on each shaft part, each of said rotary bodies comprising a rotary body part (70F.71F) being fixedly mounted on the shaft (72,73) and a rotary body part (70L, 71L) being releasably mounted on the shaft parts (72, 73), said shaft parts being interconnected through a transmission (81,82,63) so as to rotate in a opposite directions. 2. A dual vibration-compensating apparatus as claimed in claim 1, c h a ¬ r a c t e r i s e d in that the first compensating unit (51) comprises two rotary body parts, each mounted on a coaxially arranged shaft part and each having a fixed and releasable rotary body part, and being connected so as to rotate in opposite directions. 3. A dual vibration-compensating apparatus as claimed in claim 1 or 2, c h a r a c t e r i s e d in that the transmission between the two vibration-com¬ pensating units (52;53) comprises at least one coupling (62;83) being releasable to enable turning of the shaft (57) of the first compensating units (51) relative to the shaft parts (72,73) of the second compensating units (52). 4. A dual vibration-compensating apparatus as claimed in one or more of the preceding claims 1-3, characterised in that the transmission (81,82, 63) between the two shaft parts (72,73) of the second compensating units (52) comprises a releasable coupling (83) being releasable to enable turning of the two shaft parts relative to each other.

Inventors: MADSEN JOHN GRAM, MADSEN, JOHN, GRAM
Applicants: MADSEN JOHN GRAM, SMIDTH & CO AS F L, F.L. SMIDTH & CO. A/S, MADSEN, JOHN, GRAM
Application year: 1994
Main classification: F16F15
IPC codes: B63H21, F16F15